1. Field of the Invention
The invention relates to a liquid crystal display (LCD) and a backlight module (BLM), and more particularly, to an LCD and a BLM with specially designed light source and assembly elements.
2. Description of the Prior Art
LCDs have been vigorous developed, whether in small-size or large-size applications. Because liquid crystal displays (LCD) have light weight, thinness, low energy requirements, no radiation, and other good qualities, they have become the main stream in the market. Therefore, LCDs are widely applied to various information devices, such as notebooks, mobile phones, digital cameras, or personal digital assistants (PDAs), and tend to replace conventional cathode ray tube (CRT) televisions, rear projection type televisions, or plasma display panel (PDP) televisions.
Since liquid crystal molecules do not produce light themselves, the BLM is one of the major components of an LCD. The traditional BLM uses cold cathode fluorescent lamp (CCFL) as a light source. FIG. 1 is a partial sectional-view of the BLM according to the prior art. The prior-art BLM 10 includes a light guide plate 14, a CCFL 12 positioned near the light guide plate 14, a reflector 16 below the light guide plate 14, several optical films 18 on the light guide plate 14, and a frame 20 for fixing the elements of the BLM 10. Since the CCFL 12 produces light from each sides of its tube, a light source reflector 22 has to be disposed near the CCFL 12 in order to reflect light back to the CCFL 12 or the light guide plate 14 so as to raise light utility. Furthermore, for avoiding light loss from the top side of the spacing between the light source reflector 22 and the optical films 18, a shadow tape 24 has to be disposed, covering the spacing of the light source reflector 22 and the optical films 18.
However, the CCFL light source has gradually not able to satisfy consumers' requirement because the LCD using the CCFL as a light source is limited in color specification improvement. In addition, a CCFL has mercury that does not meet green product requirements. In recent years, light emitting diodes (LEDs) have been applied to BLMs for serving as light sources. Because LEDs have the advantages of high color saturation, quick response, and small size, they are popular in small-size LCDs. However, technology of white LED producing saturated white light is not mature, and therefore red LED, green LED, and blue LED are used in a BLM at the same time in many cases. In this situation, good light mixing design for sufficiently mixing red, green, and blue lights is required. Therefore, LED BLMs have complicated mechanical structures and higher costs than conventional CCFL BLMs.
U.S. Pat. No. 6,930,737 and US published application No. 2005-0157521 have disclosed conventional LCD structures with LEDs as light sources. According to U.S. Pat. No. 6,930,737, with reference to FIG. 2, an LCD device 50 includes a housing 52, a frame 72, a liquid crystal panel 54, optical films 56, a light pipe 60, enhanced specular reflector (ESR) 70, a printed circuit board (PCB) 62, LED arrays 64, 66, an enhanced diffuser reflector 68, a LED controller circuit (not shown), and a circuit board (not shown). The optical films 56, light pipe 60, ESRs 70, PCB 62, LED arrays 64, 66, and enhanced diffuser reflector 68 contained in the frame 72 compose the BLM 58 of the LCD device 50. Noted that the frame 72 includes a front frame and a rear frame for fixing the BLM 58, wherein the LED arrays 64, 66 are positioned at two sides of the BLM 58 so that light produced from the LEDs may penetrate into the light pipe 60 through its sidewalls. For avoiding light leak, the ESRs 70 have to be set for fixing the LED arrays 64, 66 near the light pipe 60 and reflecting light, with large emitting angles, back into the light pipe 60 in order to raise light utility. Accordingly, lots of assembly components are used to compose the LCD 58 for fixing all the optical elements and providing a preferable performance. Therefore, to assemble the LCD device 50 or BLM 58 shown in FIG. 2 is complicated and needs a lot of time.
As a result, to provide an improved BLM or LCD device that has good light source performance and a simple structure for simplifying the assembly process is still an important issue for the manufacturers.